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Lawn Care for Minnesota Landscapesby Diana Rankin - posted 04/30/14

Fertilizing in September and staying on top of weeds are the best ways to keep the lawn green and growing. 1

Deb Brown, garden writer and retired University of Minnesota Extension horticulturist, thinks maybe so. In a newspaper article a while back, she made some very good arguments for having a yard and garden with at least some turfgrass. Here’s her thinking:

Having a lawn is less work than maintaining a small prairie in a front yard.

The green color of turfgrass complements annual and perennial flowerbeds.

Grass can provide logical pathways between and around beds.

When it rains, a healthy lawn absorbs pollutants, such as pollen and dust, and prevents runoff and erosion.

Grass provides natural air conditioning around a home or other buildings. A lawn on a summer day is 40-60 degrees cooler than a sidewalk or parking lot.

The lawn that Brown and other University of Minnesota Extension Educators have in mind is not the lush, chemically dependent, water thirsty carpet that so many homeowners desire. Instead, they are advocating for a healthy lawn, maintained by low input lawn care practices timed to meet the needs of the Upper Midwest’s cool-season grasses.

Fall Care

Fall is an especially important time for lawn care, no matter how neglected the lawn may have been over the hot summer.

First of all, before the end of September, put down nitrogen fertilizer at the rate of one pound per 1,000 square feet. The grass plant roots are growing now and will readily absorb nitrogen. Research has found that later applications into November, as has been the common practice, are wasted because plants have stopped growing in northern gardens and cannot take up the nitrogen. If using a slow-release organic form of nitrogen fertilizer, apply it at half the rate.

This is also the best time to control broadleaf perennial weeds, such as plantain and dandelions. These plants are also growing vigorously and storing up nutrients and will actively take up and transport broadleaf weed killer throughout the plant. This should be done by early October. The plants will be killed in the fall, but the difference won’t be noticed until the next spring. Combination nitrogen fertilizer-herbicide granular products can be purchased, but the grass and weeds must be wet when it is applied. This product should not be spread too close to trees and shrubs as the herbicide can make its way through the soil to roots, killing these plants.

A granular fertilizer and a selective post-emergence liquid herbicide can also be purchased and used separately. A selective herbicide is one that will kill only certain plants, not both the broad leaves and the lawn grasses. Probably the best known herbicide, glyphosate, is non-selective and will kill everything herbaceous that it touches. Whenever using an herbicide, always read the label carefully and follow the instructions. There are also cautions about applying products before and after rain, use around water, pets, children, when you can walk on the treated area and more, on the product label

Digging or pulling broadleaf lawn weeds in the fall will greatly reduce a spring crop. This usually is not practical for large, heavily infested areas. Just remember that there is no easy, sure-fire way to rid a lawn of weeds. It may be wise to learn to tolerate a few weeds and use herbicides only when the health of the lawn is threatened.

During September maintain a mowing height of about 2 ½ to 3 inches and then gradually lower the height in October. Longer grass blades in September allow the plants to make more food via photosynthesis. This means the roots will extend deeper into the soil. Developing a strong root system creates a healthier plant. By late October, the height should have been reduced to about 2 to 2 ½ inches. Shorter grass prevents matting and the formation of snow mold the following spring.

Continue watering during dry periods. Even though temperatures are cooler and days are getting shorter, soil will still dry out if there’s no rain. Just be sure to allow the soil to dry slightly before watering again. A well-watered lawn helps prepare the grass plants for a harsh winter.

Finally, this is a great time to seed or reseed areas of the lawn. The soil is still warm and there is usually ample moisture. Another advantage is that the annual weed seeds from crabgrass, yellow foxtail, lambs quarters or common ragweed are no longer germinating. Weeds have stopped growing and are not competing with the grass seed for water and nutrients.

Winter Care

Avoid walking on frozen or frosted lawn. This can damage or break the blades of grass, resulting in brown, trampled lawn in spring.

Spring Care

Homeowners typically begin thinking about lawn care in the spring. It is a great time to seed new lawns or patch up sparse areas. Fine fescues are the most commonly used grasses in our area. They grow vigorously in the spring and fall and slow down during hot, mid-summer when it is likely to be drier. They are fine textured, medium green, drought tolerant and often mixed with Kentucky blue grass in seed mixes. Some mixes are labeled low-maintenance, indicating a reduced need for watering and fertilization.

Fertilization should begin in the spring because most root growth and the initiation of new roots are beginning. How much fertilizer to apply, however, varies with a lawn’s soil type, how much sun it receives, whether it will be irrigated, whether clippings from mowing will be left on the lawn and how much fertilizer was applied in fall.

For example, a lawn that is in full sun, not irrigated, has low soil organic matter and retains the clippings requires one-half pound of 50 percent slow release nitrogen per 1,000 square feet on or about Memorial Day. If the lawn has high soil organic matter, spring fertilization would not be recommended. Irrigated lawns, on the other hand, require more nitrogen, generally 1/2 pound of 20 to 25 percent slow-release nitrogen per 1,000 square feet at the first mowing and 1/2 pound of 50 percent slow-release nitrogen at or about Memorial Day.

Weed control is another spring activity, but only for summer annual broadleaf weeds, such as knotweed, spurge and grassy weeds, such as crabgrass and foxtail. For the broadleaf weeds, apply an herbicide when the soil is moist and weeds are young and actively growing. To control the grasses use a pre-emergence herbicide two to three weeks before weed seeds can be expected to germinate. Whenever using any herbicide, always read and follow the label directions.

The best way to tackle perennial weeds, such as dandelion and plantain in the spring is to dig them out or spot treat with an herbicide.

Begin regular mowing and leave the clippings on the lawn. Over the course of the season the clippings will provide the equivalent of about one fertilizer application annually. Bag the clippings only if a mowing is missed and they clump on the surface of the lawn.

If drought conditions have persisted through the winter and into the early spring, consider watering beginning the first week of May. No matter whether you water in spring, summer or fall, the most important thing to remember is that it should be deep and infrequent. It’s best to water in the morning and long enough to wet the soil to a depth of 5 inches. If watering a newly seeded area, apply ½ inch of water to settle the seed and then to keep the area damp, but not soggy, for three to four weeks.

Summer Care

Grass shoots grow rapidly during the summer, so the most important summer lawn care task is mowing regularly. Mow high, setting the mower’s cutting height to 3 to 3 1/2 inches (or as low as 2 1/2 inches if there has been plenty of rain). Avoid scalping the lawn to prevent moisture loss and heat stress on the grass plants.

June through early July is the best time for applying crabgrass post-emergence herbicide. Perennial weeds such as dandelions and thistles can be spot-treated with herbicide.

Mow the grass to about 3 inches high to prevent scalping and drying out of lawns. 2

Conclusion

Lawns are an important part of our public and private spaces and caring for them sustainably is more complicated than mowing, watering and randomly applying fertilizers and herbicides.

Diana Rankin is a University of Minnesota Extension master gardener, a professional writer and a member of the Grants Professional Association. Diana lives on 69 acres in USDA Zone 3, where she has seven different perennial gardens.

The views and opinions expressed in this article are those of the author alone and do not necessarily reflect the views or opinions of State-by-State Gardening, its parent company or affiliates. The author is solely responsible for all content. Our articles are only meant to educate and entertain our readers. We are not medical professionals and cannot recommend the ingestion or topical application of any herbal remedy, poultice, tea, etc. Please consult a medical professional before ingesting any plant.